Dolomitization of primarily calcarenite beds of Upper Jurassic age, deposited in the intertidal zone, is recognized in HaMakhtesh HaQatan in southern Israel. Such dolomitization is interpreted as having occurred in the supratidal zone after deposition of the carbonate sediments, and was later followed by partial dedolomitization of the same rocks. Dolomitization is attributed to reflux of hypersaline water, whereas dedolomitization appears related to exposure of the lithified sediment during the development of the Juro-Cretaceous or later unconformities. Small channels are observed arrayed in two systems perpendicular to one another on a carbonate bed. The pattern of channels is interpreted to represent a series of mega mud cracks developed within the supratidal zone and later enlarged by solution.